New IC technologies have increased the resolution and throughput of these instruments,
allowing new applications to be serviced.

» by Tim Studt, Editorial Director

Ion chromatography (IC) is an established procedure that allows researchers to separate ions and polar molecules based upon their charge. “The most important characteristic of IC that researchers look for when purchasing a new IC instrument is ease-of-use, robust and
rugged hardware along with high throughput,” says Jay Gandhi, Business
Development Manager at Metrohm USA, Riverview, Fla. When asked
what has changed the most over the past several years in IC technologies,
Gandhi says “new and miniaturized electronics have made the instruments
smaller with better sensitivity. The highest growth in new applications for
IC will come from water-related applications in terms of drinking water,
ground water and water for power generation. Due to natural gas extraction from the ground from fracking processes, water quality control for
environmental reasons will ensure premium growth.”

Combustion IC

Metrohm has offered a variety of IC systems for research lab and industrial applications for many years. Its new Combustion IC system (CIC) is
the modern combination of hydropyrolysis and IC. With this coupling,
it is possible to analyze solids and highly viscous samples fully automatically. In contrast to previous methodologies, Analytik Jena's flame sensor
technology in combination with Metrohm's liquid handling capabilities
enables fully automated analyses without time-consuming method development, internal standards and numerous manual steps. With the CIC,
even the supply of the sample is automated.

The new 881 Metrohm CIC includes all components required for com-busion digestion (combustion IC). The system is controlled by MagIC Net,
and combustion is optimized by a flame sensor. The 881 also enables the
analysis of halogens and sulfur in flammable samples of all types (
including fuels, lubricants, additives, other petroleum products, polymers, flame
retardants, textiles, special chemicals and catalysts) using inline combustion
digestion with subsequent IC determination. Unlike the conventional offline combustion methods, which are labor-intensive and often lack reproducibility and accuracy, CIC can separate and quantitate different halogens.
Digestion by pyrolysis is far superior to any offline digestion method with
regard to sample throughput, accuracy and precision. CIC is ideal for routine analyses in a variety of fields, as prior knowledge about the sample
matrix or complicated method development is not required. Additionally,
CIC complies with new and upcoming environmental requirements and
regulations, including those generated by the ASTM, DIN, EN, IEC, RoHS
and WEEE.

Metrohm's 881 contains all required components for CIC (i.e., the
Combustion Module from Analytik Jena, the 920 Absorber Module, the
881 Compact IC pro–anion–MCS and MagIC Net software). If necessary,
the 881 CIC can be supplemented with a MMS 5000 Autosampler manufactured by Analytik Jena for solid or liquid samples. The entire analysis,
including sample input and digestion, is completely automated and controlled by MagIC Net.

The overall operating principle of CIC starts with samples (such as
sulfur and halogen compounds) that are first digested under an argon
atmosphere in an oven unit and then burnt with oxygen (to form their
respective ions—SO4, F, Cl, Br and I). In the 920 Absorber Module, the
resulting gaseous compounds are then passed into an absorption solution
(such as hydrogen peroxide), which is transferred over to an anion preconcentration column that is then washed with deionized water to remove
the absorption solution in order to eliminate potential interference with
the IC analysis. The ions trapped/concentrated in the preconcentration
column are then injected into the IC for separation and detection.

The Combustion Module enables the sample digestion of flammable
samples of all types under pyrolysis and oxidation. The Combustion
Module contains a combustion oven and an Auto Boat Driver (automatic
sample introduction). Both are products of Analytik Jena and optimized
specifically for coupling with ion chromatographs. The sample combustion
process is controlled by a flame sensor, which measures the light from the
pyrolysis oven and controls the feed rate of the sample boat into the oven
based on the intensity of the light emitted during combustion. This optimizes the combustion process by achieving complete combustion of the sample
and preventing soot formation. The automated control of the sample digestion eliminates any need for method development for combustion.

Applications for CIC

The production of ultrapure water for the pharmaceutical or semiconductor industries requires high-quality ion exchangers. Metrohm CIC
is an invaluable tool for testing the purity of anion-exchanger materials.
The Restriction of Hazardous Substances Directive (RoHS) also requires
the reduction of the halogen content in several organic materials used in
electrical and electronic equipment. In this context, there is a large interest
for using halogen-free polymers. To check for these halogens in polymers,
CIC applying flame sensor technologies and Inline Matrix Elimination is
an indispensable method.

Another important application for CIC involves the detection of chlorides
and sulfur in cyclohexane, an important organic solvent. Recycled cyclohexane needs to be checked for traces of chloride and sulfates, and CIC with its